There re so many ways to do that.
1-Using ssh or similar prog. to sent them 2 iphone.You should do this manually to right folder.
2-If u didnt make it before,i advise 2 u to use a ringtone prog.There re so many.Im using iphone ringtonemaker.Its fine&easy to use it.Just select ur mp3&then cut it,tap 'create ringtone'button.Then it'ıı be sent 2 ur iphone automaticly.Thats it...
iringer is awesome for ringtones and it sends it directly to itunes. All you do is sync.. As far as a sms, you need to convert the file to .caf and replace the stock file with it, ssh is the only way to do it..You can use diskaid to access the stock files on your phone